Numerical shake prediction for earthquake early warning incorporating heterogeneous attenuation structure: The case of the 2016 kumamoto earthquake

Schemes for predicting seismic ground motion, including real-time prediction (earthquake early warning [EEW]), ideally should incorporate the effects of the source, path, and site amplification terms. In this study, we incorporated the path term into the numerical shake prediction scheme, a promising approach to EEW, in an effort to predict future ground motions with a heterogeneous attenuation structure. We characterized the heterogeneous attenuation structure of southwestern Japan using multiple lapse time window analysis, then incorporated that attenuation structure in a simulation of ground-motion prediction for the largest earthquake (M_w 7.0) of the 2016 Kumamoto earthquake sequence. The heterogeneous attenuation structure led to improvements over a homogeneous structure: the root mean square residuals of the predicted seismic intensities were 12% lower for predictions 10 s ahead and 15% lower for predictions 20 s ahead, suggesting that the benefit of using a heterogeneous attenuation structure is greater for longer lead times. Our results show that details of the attenuation structure should be considered to lengthen the lead time of ground-motion predictions by the numerical shake prediction scheme.